Research examining the extent that people's attitudes toward abortion vary across the life course is mixed. Some studies do not show a strong relationship between abortion attitudes and life stage, while others do find strong associations in both directions-older age associated with both more and less favorable attitudes toward legal abortion. Taken together, these findings suggest that individual attitudes toward abortion are static for some but malleable for others. Little is known about the prevalence, reasons, and directionality of attitude changes. This explanatory sequential mixed methods study investigates people's perceptions of whether, how, why, and for whom their abortion attitudes may have changed over their life course. We qualitatively investigated the reasons (e.g., experiences, life events) that triggered changes in respondents' abortion attitudes and quantitatively explored the sociodemographic factors associated with the perceived direction of those changes. The quantitative data come from a 2020 online survey completed by 1501 English and Spanish-speaking adults in the US. Qualitative data were collected from a subsample (n=24) of the survey respondents who indicated interest in a follow-up in-depth interview. Our findings indicate that access to information and knowledge played an important role in changing abortion attitudes across a spectrum of support or opposition. For those who indicated becoming more opposed to abortion over time, experiencing parenthood was an important trigger for change and family/religious upbringing were key to shaping attitudes. For those who became more supportive of abortion over time, empathy for women was an important trigger for change and disagreeing with or distancing oneself from family/religious upbringing were key to shaping their attitudes. If attitudinal change occurs, becoming more supportive of abortion over the life-course is more common than becoming more opposed, however there are some nuances across age and gender. Understanding the different factors that influence attitudinal change regarding abortion has important implications for public opinion research and possible ramifications for abortion legality.